3 YEARS CLINICAL-EXPERIENCE WITH GLASS-IONOMER CEMENT IN RECONSTRUCTIVE SURGERY OF THE MIDDLE-EAR

For nearly three years we have been using implants of Polymaleinate ionomer in the reconstruction of the ossicle chain (Figure 1). Implants of this material can be easily formed by a diamond drill. An implant in site 18 months later is to be seen in Figure 2. From August 1990 through April 1993 this material has been implanted into 156 middle ears. Only one implant had to be explanted again for a second-look operation in cholesteatoma. Extrusion or any tissue reaction on the foreign substance could not be seen. The implant was examined histologically. It was covered by mucosa and not destructed anyway (Figure 3). According to the extension of a cholesteatoma we take away the dorsal wall of the ear canal for reasons of sanitation and leave a radical mastoid cavity in children. In adult patients we tend to reconstruct the ear-canal to avoid the disadvantages of a radical mastoid cavity: Frequent treatments and hearing-loss by resonance-shifting (2). For reconstructing the dorsal wall of the ear-canal cartilage of the concha and tragus is well qualified. In support of experimental and clinical experience of the Wurzburg group (1) we take ionomer micro-implants for reducing large radical mastoid cavities (Figure 4). The radical mastoid cavity is finished by the diamond-drill before being filled up with micro-implant in the dorsal parts. The micro-implant is covered by a flap of periost and connecting tissue. Figure 5 shows a situation operated by this technique 20 months ago, Figure 6 shows the result after operation of a former secerning radical mastoid cavity. The ear-canal has a nearly normal volume. We reduced the radical mastoid cavity in 15 patients after operation of a cholesteatoma by micro-implant in this way. Only in one patient a pearl of cholesteatoma had to be removed from the rim of the implants bed without removing the implant itself. We believe that the palva flap had covered the material insufficiently in this case, so that epithelium immigrated to form the pearl of cholesteatoma. Histology showed a unaffected imbedding of the implant of the implant particles in the meshwork of the connective tissue. The advantage of the ionomer micro-implant, however, is that its particles do not form a bony connection but are surrounded by fibres of connecting tissue (1). This enables a recurring cholesteatoma to penetrate towards the lumen of the ear-canal instead of destroying the bone by subsequent intracranial complications. In all patients epithelisation of the micro-implant was completed after 6 months. No granulations or infections occurred.